An oscilloscope as a type of signal measuring device and is used to qualitatively and quantitatively analyze a signal to be measured, typically but not exclusively in the time-domain. The oscilloscope displays an analog graphical representation of one or more of its input channels.
In the publication WO 2008/064752 A1 a method and a system for determining a statistic measurement parameter is disclosed. The continuous updating of the display unit of a measuring device with a current frequency-distribution of a signal level of an applied waveform against time or frequency allows only the presentation of the current frequency distribution of a stochastic signal. Therefore, within an observation interval, the frequency of the signal levels of the applied waveform is counted from new, buffered and presented for display on a display device. A respective statistical parameter is determined from the currently-counted frequency and from the frequency measured and buffered respectively in earlier observation intervals and re-buffered.
Nowadays, measuring devices are able to display waveforms or graphical representations of input channels. In persistence mode of the measuring device the frequency distribution is accumulated over a plurality of waveforms and thus a sum of the frequency distribution is obtained.
Additionally, it is known to present the frequency distribution information of a waveform not only by increasing or decreasing of the contrast values of the displayed signal. It is also possible to use a color spectrum to present such waveform frequency distribution information.
It is also known to use a so-called “track-function” of a measuring device. A track is a waveform that shows measurement values in time-correlation to the signal to be measured. Thus, the track-function is the graphical interpretation of all measurement values of a single acquisition. Thus, using the track-function, a signal parameter can be derived from the signal over a plurality of waveforms. This is specifically applicable for periodic signals in which a specific signal parameter is obtained in each period of the signal to be measured. Thus, signal parameters can be derived over frequency or time and can be analyzed due to changes of their signal parameter characteristics.
Nowadays, signal parameters that are derived with such a track-function of a signal measuring device are displayed on a separate diagram on a display unit of the measuring device apart from the diagram on which the signal itself is displayed. In case the signal to be analyzed needs to be detected over large time durations, the variations of the track-function is heavily reduced and compressed in a manner that details cannot be derived from this track-function plot. It is nearly impossible to efficiently analyze the signal parameter.
To somehow analyze such a signal, the user is forced to use a zoom-function of the measuring device to obtain detailed information from the track-function plot of the signal parameter. Since the user cannot figure out in which part of the waveform it should be zoomed in, he is forced to randomly pick a specific region of the signal for zooming in. In case the signal parameter does not include any abnormal behavior in the randomly picked region, another region of the signal has to be chosen and zoomed. The analysis is thus a trial-and-error method which is inefficient and time-consuming. Also, It is thus questionable whether the user is actually able to identify any abnormal behavior of the signal parameter.
What is needed, therefore, is a measuring approach whereby a signal parameter of a signal to be measured is presented on a display unit of the measuring device in a more efficient way and without the risk of missing any abnormal behavior or regions of interests in the signal.